Food availability to natural oyster populations: Food, flow and flux


1993 2003 May 31


Wilson-Ormond E
Powell EN
Hofmann EE
Klinck JM

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Food availability to natural oyster (Crassostrea virginica) populations is dependent upon the quantity of food present, water flow speed, and oyster density. Field experiments were conducted (Confederate Reef, Galveston Bay, TX) to determine the temporal variability in the food concentration and water flow speed on scales consistent with oyster feeding. Results indicate that the amount of food (mg/l) available to the population is highly variable on temporal scales as short as 3 hr. Water flow speeds (cm/s) are also quite variable, however, they tend to cluster about a narrow range of slower speeds. The resultant food fluxes (mg cm super(-2)/s) indicate that natural populations experience a highly variable food supply. Rapid water flow can compensate for low food concentration by resulting in an overall higher flux of food, while slow flow typically results in low flux regardless of the concentration of food. These results suggest that in some cases, water flow speed is more important than food concentration in determining the amount of food available to the population. A mathematical model of oyster energetics was employed to further assess the role of water flow in determining productivity in natural oyster populations. Simulation results suggest that oyster productivity is higher under conditions of rapid flow because of increased food availability due to a higher flux of food particles. Slower water flow can result in food depletion due to overfiltration and can ultimately reduce productivity. Productivity was better estimated in simulations using the variable food supply as compared to the average food supply. The latter consistently overestimated productivity. Therefore, the short-term temporal variability in available food is an important factor affecting oyster feeding and productivity




ASW,USA,Texas,Galveston Bay, biological production, Crassostrea, Crassostrea virginica, Current velocity, Filter feeders, food availability, Galveston Bay, Mathematical, natural populations, Populations, Q1 01264 Reproduction and development, Q1 01422 Environmental effects, Q1 01482 Ecosystems and energetics, Q1 01583 Shellfish culture, Q3 01583 Shellfish culture, Shellfish, simulation, temporal variations, Texas, USA, Variability, water, Water currents